This project will compare the binocular mechanisms that process image correspondence information for the control of vergence eye movements, the perception of stereoscopic depth and the maintenance of single vision. The purpose is to attain an integrated understanding of sensory an motor processing of retinal disparity. The knowledge gained will lead eventually to the diagnosis and treatment of binocular visual disorders, and will provide tools for the study of the development of binocular visual function. One series of experiments examines the spatial constraints on binocular matching, using dynamic random dot stereogram stimuli. Proposed psychophysical experiments will compare the range of horizontal and vertical disparities which give rise to stereoscopic depth. Oculomotor experiments will measure the range of horizontal and vertical disparities which give rise to voluntary and involuntary changes in vergence. The comparison of oculomotor and psychophysical results will test the validity of the distinction between voluntary and involuntary vergence and will clarify the degree to which these two types of vergence interact with perceived depth. A second series of experiments examines the sensitivity of binocular matching on the vertical disparity axis, again using dynamic random dot stereogram stimuli, and compares it to the sensitivity of monocular pattern recognition mechanisms which analyze the self-similarity of images. Proposed psychophysical experiments will measure the degree of image self- similarity required to elicit a "Glass pattern" percept for a given amount of image shift. These results will be compared to those of experiments which measure the degree of left and right image similarity required to elicit a dichoptic "Glass pattern" percept for a give amount of image disparity. Subsequent experiments will combine monocular and dichoptic Glass pattern stimuli in order o measure fusion ranges on the vertical disparity axis. Oculomotor experiments will measure the degree of left and right image similarity required to elicit a vergence eye movement int he appropriate direction, as a function of vertical disparity.